Abstract

The study of flow dynamics in complex geometry vessels is highly important in many
biomedical applications where the knowledge of the mechanic interactions between the
moving fluid and the housing media plays a key role for the determination of the
parameters of interest, including the effect of blood flow on the possible rupture of
atherosclerotic plaques. Doppler Optical Coherence Tomography (DOCT) is an optic,
non-contact, non-invasive technique able to achieve detailed analysis of the flow/vessel
interactions, allowing simultaneously high resolution imaging of the morphology and
composition of the vessel and of the flow velocity distribution along the measured
cross-section. DOCT system was developed to image high-resolution one-dimensional
and multi-dimensional velocity distribution profiles of Newtonian and non-Newtonian
fluids flowing in vessels with complex geometry, including Y-shaped and T-shaped
vessels, vessels with aneurism, bifurcated vessels with deployed stent and scaffolds.
The phantoms were built to study the interaction of the flow dynamics with different
channel geometries and to map the related velocity profiles at several inlet volume flow
rates. Feasibility studies for quantitative observation of the turbulence of flows arising
within the complex geometry vessels are discussed. In addition, optical clearing of skin
tissues has been utilized to achieve DOCT imaging of human blood vessels in vivo, at a
depth up to 1.7 mm. Two-dimensional OCT images of complex flow velocity profiles in
blood vessel phantom and in vivo subcutaneous human skin tissues are presented. The
effect of optical clearing on in vivo images is demonstrated and discussed. DOCT was
also applied for imaging scaffold structures and for mapping flow distributions within
the scaffold